diff options
| -rw-r--r-- | tools/lib/bpf/gen_loader.c | 39 |
1 files changed, 24 insertions, 15 deletions
diff --git a/tools/lib/bpf/gen_loader.c b/tools/lib/bpf/gen_loader.c index 66a02039da8c..a5d9c7a5261b 100644 --- a/tools/lib/bpf/gen_loader.c +++ b/tools/lib/bpf/gen_loader.c @@ -1187,27 +1187,36 @@ void bpf_gen__map_update_elem(struct bpf_gen *gen, int map_idx, void *pvalue, value = add_data(gen, pvalue, value_size); key = add_data(gen, &zero, sizeof(zero)); - /* if (map_desc[map_idx].initial_value) { + /* + * if (map_desc[map_idx].initial_value) { * if (ctx->flags & BPF_SKEL_KERNEL) * bpf_probe_read_kernel(value, value_size, initial_value); * else * bpf_copy_from_user(value, value_size, initial_value); * } + * + * The runtime initial_value comes from the host-supplied loader + * ctx and would overwrite the blob value after emit_signature_match() + * has already validated map->sha[]. For a signed loader (gen_hash) + * the attested blob value must be authoritative, so skip the override + * and leave the hashed value in place. */ - emit(gen, BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_6, - sizeof(struct bpf_loader_ctx) + - sizeof(struct bpf_map_desc) * map_idx + - offsetof(struct bpf_map_desc, initial_value))); - emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_3, 0, 8)); - emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE, - 0, 0, 0, value)); - emit(gen, BPF_MOV64_IMM(BPF_REG_2, value_size)); - emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6, - offsetof(struct bpf_loader_ctx, flags))); - emit(gen, BPF_JMP_IMM(BPF_JSET, BPF_REG_0, BPF_SKEL_KERNEL, 2)); - emit(gen, BPF_EMIT_CALL(BPF_FUNC_copy_from_user)); - emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 1)); - emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel)); + if (!OPTS_GET(gen->opts, gen_hash, false)) { + emit(gen, BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_6, + sizeof(struct bpf_loader_ctx) + + sizeof(struct bpf_map_desc) * map_idx + + offsetof(struct bpf_map_desc, initial_value))); + emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_3, 0, 8)); + emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE, + 0, 0, 0, value)); + emit(gen, BPF_MOV64_IMM(BPF_REG_2, value_size)); + emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6, + offsetof(struct bpf_loader_ctx, flags))); + emit(gen, BPF_JMP_IMM(BPF_JSET, BPF_REG_0, BPF_SKEL_KERNEL, 2)); + emit(gen, BPF_EMIT_CALL(BPF_FUNC_copy_from_user)); + emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 1)); + emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel)); + } map_update_attr = add_data(gen, &attr, attr_size); pr_debug("gen: map_update_elem: idx %d, value: off %d size %d, attr: off %d size %d\n", |